Method and Jetting Head for Making a Long and Narrow Penetration in the Ground

ABSTRACT

A method is for making a relatively long and narrow penetration in the ground where a jetting head that has a longitudinal axis is attached to a leading end of a tubular. The method comprises providing the jetting head with at least one fixed nozzle that is positioned at the leading end portion of the jetting head and where the fixed nozzle has an elongated cross section; and flowing liquid through the nozzle where a resulting liquid fan is directed towards the ground in front of the jetting head.

FIELD

There is provided method for making a long and narrow penetration in the ground. More precisely there is provided a method for making a long and narrow penetration in the ground where a jetting head that has a longitudinal axis is attached to a leading end of a tubular. The invention also includes a jetting head for performing the method.

BACKGROUND

Relatively long, narrow or small diameter, penetrations in the ground, including rock formations, may be required. Typically narrow penetrations may be used for extraction of hydrocarbons, but such penetrations may also be used for running cables in the ground without excavation, drainage of fluids or for other purposes.

Penetrations of this kind may be made by use of different jetting methods. It is known to use several independent nozzles or rotating nozzle heads in a jetting head to cover a full cross sectional area in order to enter the jetting head into the penetration. The nozzle head is inserted by the means of a fluid conduit like a hose or a tube. In most cases a flow rate will be limited in the fluid delivery system. For a limited flow rate and differential pressure a larger total number of nozzles will require that each nozzle is small compared to if a smaller number is used.

Smaller nozzles tend plug up more easily than larger nozzles, and plugging of nozzles will cause a halt of the fluid flowing through all or some of the nozzles and the penetrating progression will slow down or stop.

A rotating jetting head may be used to cover a cross sectional area large enough for the nozzle to pass through. The rotating head requires complex features like dynamic seals to reliably turn. A reliable rotating jetting head designed for through flow of a fluid that includes abrasives is still more complex due to wear on seals and other components.

Several methods have been proposed to make simple and reliable nozzles. One such example is Buckman Jet Drilling, Inc. that uses a hollow cone nozzle. Another use of cone type nozzle is fog type nozzles, i.e. nozzles that disperse the jetting energy into tiny droplets. Jetting velocity and impact against the ground is therefore lost in the nozzle.

SUMMARY

A purpose of the invention is to overcome or reduce at least one of the disadvantages of the prior art.

This purpose is achieved according to the invention by the features as disclosed in the description below and in the following patent claims.

There is provided a method for making a relatively long and narrow penetration in the ground where a jetting head that has a longitudinal axis is attached to a leading end of a tubular, wherein the method includes:

-   -   providing the jetting head with at least one fixed nozzle that         is positioned at the leading end portion of the jetting head and         where the fixed nozzle jet stream has an elongated cross         section; and     -   flowing liquid through the nozzle where a resulting liquid fan         is directed towards the ground in front of the jetting head.

The elongated nozzle will produced a liquid fan that has a larger width than thickness. The liquid fan may thus be relatively flat. This liquid fan will hit the ground along a distance equal to the length of its cross section of the liquid fan at the position of impact in front of the jetting head. The nozzle is positioned in a wall that is substantially perpendicular to the flow direction of the liquid being supplied through the tubular and into the nozzle. Hence, most of the pressure energy of the supplied liquid is transformed to fluid velocity in the nozzle.

The method may further include providing the jetting head with at least two nozzles that are spaced about the longitudinal axis of the jetting head.

Thus a more efficient penetration may be achieved as each liquid fan only has to remove material from a sector of the penetration.

The method may further include directing the fluid from the fixed nozzle at an angle relative the longitudinal axis. A still more efficient penetration may then be achieved as the position of impact on the ground will change with the distance between the jetting head and the position of impact.

The method may further include rotating the jetting head about the longitudinal axis. The rotation may be achieved by turning the tubular or by rotating the jetting head relatively to the tubular. The jetting head may be made to rotate by use of for instance an electric or hydraulic drive mechanism.

Oscillation may be induced in the nozzle to improve the sweep of the fluid jet.

The method may further include adding abrasive material in the liquid for increasing penetration efficiency.

The method may be performed by use of a jetting head for making a long and narrow penetration in the ground where a jetting head that has a longitudinal axis is attachable to a leading end of a tubular, wherein the jetting head has at least one in its cross section elongated fixed nozzle that is positioned at the leading end portion of the jetting head.

The jetting head may have at least two nozzles that are spaced about the longitudinal axis of the jetting head. The nozzles may have the largest width of their cross section in the radial direction of the jetting head.

The nozzle may be directed at an angle relative the longitudinal axis. The flow of liquid will thus depart from the nozzle at an angle to the longitudinal axis. The angle should be less than 45 degrees and preferably less than 20 degrees in order to achieve a best possible impact of the liquid at the ground.

The method and jetting head according to the invention provide an effective way of making a penetration in the ground as well as a simple jetting head without substantial losses of energy in the liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, an example of a preferred device is explained under reference to the enclosed drawings, where:

FIG. 1 shows a jetting head according to the invention at a leading end of a tubular under penetration of the ground;

FIG. 2 shows the jetting head at a larger scale;

FIG. 3 shows a cross section of the jetting head;

FIG. 4 shows side elevation of a liquid fan emerging from the jetting head;

FIG. 5 shows in a perspective view four liquid fans emerging from the jetting head;

FIG. 6 shows a front view of a jetting head having a somewhat oval form nozzle;

FIG. 7 shows a front view of a jetting head having twin nozzles;

FIG. 8 shows a front view of a jetting head having a cross type nozzle;

FIG. 9 shows a cross section of a jetting head having a nozzle pointing straight ahead; and

FIG. 10 shows a cross section of a jetting head having an inclined nozzle.

DETAILED DESCRIPTION OF THE DRAWINGS

On the drawings the reference number 1 denotes a jetting head that is positioned at the end 2 of a tubular 4, here in the form of a pipe that is forming a penetration 6 into the ground 8. The jetting head 1 and the tubular 4 have a longitudinal axis 10, see FIG. 2.

The jetting head 1 has in this preferred embodiment, a cross pattern elongated fixed nozzles 12 that are positioned at a leading end portion 14 of the jetting head 1. The nozzle 12 is spaced about the longitudinal axis 10 of the jetting head 1.

The jetting head 1 has an internal opening 16 leading to the nozzle 12 at the leading end portion 14, see FIG. 3. The jetting head 1 is adapted to be connected to the tubular 4 by way of a not shown screw connection.

In FIG. 4 a liquid fan 18 is shown emerging from one of the nozzles 10 at an angle 20 to the longitudinal axis 8. Only one liquid fan 18 is shown in FIG. 4.

In FIG. 5 four liquid fans 18 are illustrated, each emerging from its nozzle 10 at an angle 20 to the longitudinal axis 8.

When in operation, fluid under larger pressure than ambient pressure is supplied through the tubular 1, via the internal opening 16 in the jetting head 1 and through the nozzles 12. The nozzles 12 form liquid fans 18 that will impact the ground 6 in the direction of penetration. Each of the liquid fans 18 erodes a sector of the penetration 6. Each of the liquid fans 18 that are inclined relatively to longitudinal axis 10 will meet the ground at different positions when the distance between the nozzle 12, and the point of impact with the ground 8 is changed.

For penetrating some harder ground materials liquid containing abrasives may be utilized.

The jetting nozzle 1 may also be rotated or oscillated about the longitudinal axis 10 as indicated in the general part of this document.

In FIGS. 6, 7 and 8 alternative forms of the nozzles 12 are shown. In FIGS. 9 and 10 the difference between a straight nozzle and an inclined nozzle is illustrated. 

1. A method for making a relatively long and narrow penetration in the ground where a jetting head, that has a longitudinal axis, is attached to a leading end of a tubular wherein the method comprises: providing the jetting head with at least one fixed nozzle that is positioned at the leading end portion of the jetting head and where the fixed nozzle has an elongated cross section; and flowing liquid through the nozzle where a resulting liquid fan is directed towards the ground in front of the jetting head.
 2. A method according to claim 1, wherein the method further comprises providing the jetting head with at least two nozzles that are spaced about the longitudinal axis of the jetting head.
 3. A method according to claim 1, wherein the method further comprises directing the fluid from the nozzle at an angle relative the longitudinal axis.
 4. A method according to claim 1, wherein the method further comprises rotating the jetting head about the longitudinal axis.
 5. A method according to claim 1, wherein the method further comprises including abrasive material in the liquid.
 6. A jetting head for making a relatively long and narrow penetration in the ground comprising a jetting head that has a longitudinal axis and is attachable to a leading end of a tubular, wherein the jetting head has at least one in its cross section elongated fixed nozzle that is positioned at the leading end portion of the jetting head.
 7. A jetting head according to claim 6, wherein the jetting head has at least two nozzles that are spaced about the longitudinal axis of the jetting head.
 8. A jetting head according to claim 6, wherein the nozzle is directed at an angle relative the longitudinal axis.
 9. A jetting head according to claim 8, wherein the angle is less than 45 degrees. 